# Magnetic knife? **URL:** \ **Category:** Factual Questions\ **Created:** [April 18, 2000, 1:13am UTC](https://boards.straightdope.com/t/magnetic-knife/10577 "2000-04-18T01:13:00Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Ruffian](https://avatars.discourse-cdn.com/v4/letter/r/71e660/32.png) [@Ruffian](https://boards.straightdope.com/u/Ruffian)\ **Post date:** [April 18, 2000, 1:13am UTC](https://boards.straightdope.com/t/magnetic-knife/10577/1 "2000-04-18T01:13:00Z")
So my fiancé (whoo hoo! as of yesterday!) and I were having dinner last night, and he had a most unusually magnetic dinner knife. It was magnetic only at the base end, and it was potent enough to lift other utensils off the table. This has to be one of the more bizarre things I’ve witnessed. He told me that, as a kid, this had happened with him once before, except with a spoon. His parents have a picture of him holding this spoon, with another spoon dangling from it from the magnetism. What on earth would magnetize a common dinner utensil? I tried rubbing the knife on other utensils, trying to “charge” them, to no avail. Anyone ever see this? What gives? * * * Teaching: The ultimate birth control method. [Laura’s Stuff and Things](http://members.aol.com/lrconaway) ---
**Author:** ![SINsApple](https://avatars.discourse-cdn.com/v4/letter/s/eb8c5e/32.png) [@SINsApple](https://boards.straightdope.com/u/SINsApple)\ **Post date:** [April 18, 2000, 3:00am UTC](https://boards.straightdope.com/t/magnetic-knife/10577/2 "2000-04-18T03:00:00Z")
I think it has to do with the big dishwashers that restaurants use. I have had it happen to me several times, the first was in a Best Western. I don’t remember where else it has happened (the first is always the most memorable as a rule don’t you think?) * * * Rather, I was in the position of a spore which, having finally accepted its destiny as a fungus, still wonders if it might produce penicillin. –Ayi Kwei Armah ---
**Author:** ![Slithy\_Tove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/slithy_tove/32/18248_2.png) [@Slithy\_Tove](https://boards.straightdope.com/u/Slithy_Tove)\ **Post date:** [April 18, 2000, 3:22am UTC](https://boards.straightdope.com/t/magnetic-knife/10577/3 "2000-04-18T03:22:00Z")
BTW, I’ve heard that knives keep their edge longer if stored with the blades along a north/south axis. ---
**Author:** ![douglips](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@douglips](https://boards.straightdope.com/u/douglips)\ **Post date:** [April 18, 2000, 6:02am UTC](https://boards.straightdope.com/t/magnetic-knife/10577/4 "2000-04-18T06:02:00Z")
> [@](#): > > BTW, I’ve heard that knives keep their edge longer if stored with the blades along a north/south axis. Where the heck did you hear that? It smells of urban legend to me, though I can’t find it referenced anywhere. ---
**Author:** ![pluto](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@pluto](https://boards.straightdope.com/u/pluto)\ **Post date:** [April 18, 2000, 6:22am UTC](https://boards.straightdope.com/t/magnetic-knife/10577/5 "2000-04-18T06:22:00Z")
> [@](#): > > Originally posted by Ruffian: > **What on earth would magnetize a common dinner utensil** A strong magnetic field. There are lots of them in your average house, although most are shielded and/or inaccessible. Most electric motors have strong permanent magnets in them and generate even stronger magnetic fields when in operation. The dishwasher motor is a possibility – maybe the knife fell down into the bottom of the dishwasher near the motor and was magnetized. ## When I was a lad my brother brought home a school science project – a “magnetizer”. This consisted, IIRC, of a toilet paper tube wrapped with lots of copper wire that you plugged into your average wall socket. Anything made of iron and slender enough to fit inside the cardboard tube could be magnetized by this magical device. We found many such objects. Most of them were eating utensils. There was no shortage of magnetic knives at our house. “When you wake up in the morning, Pooh,” said Piglet at last, “what’s the first thing you say to yourself?” “What’s for breakfast?” said Pooh. “What do _you_ say, Piglet?” “I say, I wonder what’s going to happen exciting _today?_” said Piglet. Pooh nodded thoughtfully. “It’s the same thing,” he said. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [April 18, 2000, 3:42pm UTC](https://boards.straightdope.com/t/magnetic-knife/10577/6 "2000-04-18T15:42:00Z")
As I have come to understand it: Many metallic objects can take on magnetic properties. I believe this is known as “paramagnetism”. Typically, it can occur during the manufacturing process (unintentionally) when the forming process can cause electrons to “align” in the sense that they are said to have the same “spin” characteristic. Likewise, it is known that hitting a magnet against a hard surface can de-magnetize by knocking the electrons, all initially with the same “spin”, to now vary the “spin” value to a random distribution. Magnetism is based on the fact that the electrons of an object have the same “spin” value. (Spin is just an arbitrary term used to describe this attribute of an electron, and it is not imply the electon actually spins.) * * * “They’re coming to take me away ha-ha, ho-ho, hee-hee, to the funny farm where life is beautiful all the time… :)” - Napoleon IV ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 18, 2000, 8:55pm UTC](https://boards.straightdope.com/t/magnetic-knife/10577/7 "2000-04-18T20:55:00Z")
Actually, metals like iron, nickel, and cobalt (ferromagnetic, not paramagnetic; para- is similar but weaker and non-permanent) can actually become spontaneously magnetized from a very small stimulus: the Earth’s magnetic field, or mechanical stresses on the material. This is because, once a few magnetic domains line up, they produce a magnetic field themselves that can help align neighboring domains. * * * “There are only two things that are infinite: The Universe, and human stupidity-- and I’m not sure about the Universe” –A. Einstein ---
**Author:** ![InutilisVisEst](https://avatars.discourse-cdn.com/v4/letter/i/d2c977/32.png) [@InutilisVisEst](https://boards.straightdope.com/u/InutilisVisEst)\ **Post date:** [April 18, 2000, 9:11pm UTC](https://boards.straightdope.com/t/magnetic-knife/10577/8 "2000-04-18T21:11:00Z")
Chronos seems to pretty much have it, although the dishwasher **might** play a role: realignment of the domains is easier when the metal is struck/bent (mechanical stress) or heated. Not sure if a dishwasher (~150F) gets hot enough to help Earth’s weak magnetic field, though. I doubt the motor has a steady magnetic field capable of doing it (A/C motors are generally all windings, with no magnets), but the heating coil might develop a strong field at the instant current is cut. * * * I lead a boring life of relative unimportance. Really. ---
**Author:** ![InutilisVisEst](https://avatars.discourse-cdn.com/v4/letter/i/d2c977/32.png) [@InutilisVisEst](https://boards.straightdope.com/u/InutilisVisEst)\ **Post date:** [April 18, 2000, 9:14pm UTC](https://boards.straightdope.com/t/magnetic-knife/10577/9 "2000-04-18T21:14:00Z")
Damn: hit Submit even as it occurred to me that none of us has bothered to say: Congrats, Ruffian! Oh, and you’ll probably get more mileage (YMMV) out of your knives by turning them blade-side-up in the knife block (so they don’t cut the wood) than you will by turning them N/S.